Metals(u3a)

• Properties:

  -Metals are good conductors of heat and electricity. Metals are able to conduct electricity in both the solid and liquid states.

  -Metals have high melting and boiling points. All the metals are solids except mercury, which is liquid at room temperature.

  -Metals are strong and dense, but they are also malleable (can be hammered into shape) and ductile (can be drawn into wires).
• Test for oxygen: Oxygen can be made by heating potassium permanganate in a test tube and allowing the gas to pass through

  rocksil wool to the preheated metal as shown.

  Potassium permanganate is used because it provides more oxygen than air which only contains 20%.
• metal + oxygen -> metal oxide
• metal + water -> metal hydroxide + hydrogen
• metal + acid -> salt + hydrogen
• Electricity is a flow of charged particles:

  o flow of ELECTRONS through METALS,

  o flow of IONS through IONIC solutions or melts.
• When placed in an electrolyte metals tend to lose electrons and form positively charged ions to achieve a noble gas arrangement. This is known as oxidation
• The ion-bridge is filter paper soaked in an ionic solution, e.g. sodium chloride. The ionic solution used in the ion-bridge must always contain metal ions that are higher in the ECS than the metals being used in the half-cells or else a displacement reaction will occur.
• Electrons always flow from metals high in the electrochemical series through the wires to metals lower in the electrochemical series.

  The further apart two metals are in the electrochemical series the larger the voltage obtained.
• Redox-Chemical reactions which produce electricity are called redox (reduction and oxidation) reactions. One reactant will lose electrons (oxidation) and one will gain electrons (reduction). Both reduction and oxidation must take place for and electric current to be produced in a cell.
• The electrode in the non-metal half-cell is always made from carbon.
• Metals such as gold and silver are found uncombined on earth because they are unreactive. As a result of this, these elements were among the first to be discovered. Other metals are found in compounds called ORES and have to be extracted.

  Ores are naturally-occurring compounds of metals from which metals can be extracted. The three main types of ore are metal carbonates, metal oxide and metal sulphides.
• Most metals require to be separated (extracted) from the other elements with which they are combined in their ores. The process of making a metal from its ore is called reduction. A substance which removes the other elements from the ores is called a reducing agent.
• -Electrolysis is the decomposition of an ionic compound into its elements using electricity.

  -A d.c. supply must be used if the products of electrolysis are to be identified.

  -Positive ions gain electrons at the negative electrode and negative ions lose electrons at the positive

  electrode.
• OIL – Oxidation is the Loss of Electrons

  RIG – Reduction is the Gain of Electrons